Ultraviolet printing-out compounds



Patented Jan. 5, 1937 UNITED STATES PATENT OFFICE ULTRAVIOLET PRINTING-OUT Coll/[POUNDS No Drawing. Application September 7, 1935, Serial No. 39,626

4 Claims.

This invention relates to photographically sensitive materials and more particularly to such materials containing the silver salts of certain pyrazolone compounds and useful for printing out purposes when exposed to ultra-violet light.

Light-sensitive papers of the type which exhibit a visible image directly on exposure to light, without subsequent development, are known as printing-out papers. Such papers are useful in recording the intensity of light or the duration of exposure, as in actinometers, exposure meters, automatic recording machines, etc. These papers are usually sensitive mainly to visible light, and continue to change color on long exposure to ordinary illumination. When the intensity of light of shorter wave is to be measured, or when the exposed material is to be subjected to conditions of slight illumination, it is desirable to have a material which is relatively insensitive to visible light, and sensitive mainly to the rays to be measured.

It is accordingly the principal object of the present invention to provide a light-sensitive material which is sensitive to ultra-violet light, and relatively insensitive to visible light.

This object is accomplished by the present invention by sensitizing a colloidal material with a silver salt of certain pyrazolone compounds.

The methods by which these materials are made and their properties will now be described.

I.-Silver salt of 1-p-sulfo-phenyl-3-methyl-5- pyrazolone A water solution of 1.7 gr'ams of silver nitrate in 20 c. c. of 5% gelatin was added slowly but with vigorous stirring to a gelatin solution of 2.5 grams of l-p-sulfo-phenyl-3-methyl-5-pyrazolone. The pyrazolone was dissolved in 200 c. c. of water and then to this water solution were added 200 c. c. of a 10% gelatin sol. In the course of several minutes the emulsion assumed a tan color which would turn black if exposed to dull daylight. The emulsion was prepared in the light of a safelight transmitting orange and red light. Gelatin coated paper was coated with the emulsion of the silver pyrazolone and allowed to dry. The paper is sensitive to ultra-violet light, giving a purple print-out on a pale tan ground. Heating to C. has no efiect on the unfixed print.

II.--Silver salt of :4-suljo-phenyl-3-carboxylic acid-5-pyrazolone 50 c. c. of a 1% gelatin solution containing 1.7 grams of silver nitrate was added to 200 c. c. of

III.-Silver salt of 1-phenyl-3-carbozcylic acid-5- pyrazolone 50 c. c. of a 5% gelatin solution containing 1.7 grams of silver nitrate was added to 200 c. c. of 15 a 5% gelatin solution which was saturated with l-phenyl-B-carboxylic acid-5-pyrazolone (which contained less than 3 grams of the pyrazolone).

A cream colored emulsion was obtained after allowing it to stand for several minutes. Paper was coated as before. Exposure to ultra-violet light produces a purple image on a pale brown ground.

The image of the unflxed print can be intensified by heating it to 80 C. However, the ground 25 also becomes somewhat darker upon heating.

IV.--Silver salt of meta-nitrophenyl pyrazolone carboxylic acid The procedure as described for the preparation of the silver salt of l-phenyl-3-carboxylic acid- 5-pyrazolone was followed. Upon exposure to the ultra-violet light a pale purple image on a pale yellow ground is obtained. Heating has no intensifying action on the image but does cause the entire gelatin layer to rise (become thicker).

In every case the unaffected salt can be removed in sodium thiosulf ate thus offering a means of fixation of the print. The layer is relatively insensitive to visible light so that fixing is not 40 necessary when the prints are kept in conditions of ordinary indoor illumination.

What we claim is:

1. A photographic material sensitive to ultraviolet light and comprising a colloid carrier and 45 a photo-sensitive material, the sensitive material being a silver salt of one of the following pyra- I zolone compounds: 1-p-sulfo-phenyl-3-methyl- I S-pyraz'olone, 4-sulfo-phenyl-3-carboxylic acid- 5-pyraz'olone, 1-phenyl-3-carboxylic acid-5-py- 50 razolone, and meta-nitrophenyl pyrazolone car boxylic acid.

2. A photographic material sensitive to ultraviolet light and comprising a colloid carrier and a photosensitive material, the sensitive material 55 4. A photographic material sensitive to ultraviolet light and comprising a colloid carrier and a photosensitive material, the sensitive material being a silver salt of 1-phenyl-3-carboxylic acid- 5-pyrazolone.

SAMUEL E. SHEPPARD. WALDEMAR VANSELOW. 

